With my largest snake (who is smaller than yours, by far) I give her 2-4 pinkies (we only buy pinkies) and leave it at that, but every so often, about 5 days after eating, I give her a night crawler or two as a treat. That's what she started eating when I first caught her, so it's always a big treat since she hates fish. I find variety is the best diet, so if you feed her less mice, you could add some worms in with it too.